Star Trek is here, finally; or here again, I should say. The new movie, of course, re-invents the original characters and for my money, that original series is still the best. I always found that none of the other incarnations could ever capture quite the same powerful, dynamic characters or the same sense of adventure.
If you've seen all the original episodes so many times you know them by heart (I can't be the only one who did that), or if you just want to immerse yourself in the experience in a different way, grab one of the Star Trek Key Collections (by Giotti), which compile the run of Star Trek comics from the late 60's and early 70's.
As with the episodes themselves (and with any good sci-fi), these stories are loaded with interesting ideas and speculation. In "Museum at the End of Time" (Volume 2), the Enterprise is trapped in a cosmic Bermuda Triangle and must cooperate with the warlike Klingons to escape. In "the Choice" (Volume 4), Captain Kirk's double from alternate timeline forces the crew to confront questions of destiny and free will. These stories also made clever use of the fact that they had no budget constraints and could put the crew into larger, more epic situations that wouldn't have been economical for a weekly television show, like taking on an army of automated destroyers (Volume 1) or dealing with a hostage situation involving an entire miniaturized planet (Volume 3).
The art is impressively gritty and textured and the action has an impressively realistic energy. Volume 2 also features early stories by Len Wein, who went on to co-create both the Swamp Thing and Wolverine (!).
Is it a flawless Star Trek experience? That would be stretching it. Are some of the ideas loopy? Yes, particularly in Volume 1, where things like voodoo dolls make a difficult match with science fiction. Are the phasers pink? Well, yes, they are. In the early volumes, some of the figural and color art (as well as the written depiction of some of the characters) is not exactly consistent with the show. But with eight complete adventures in each volume, that's a lot of bang for your buck, and these things are a huge amount of fun.
Meanwhile, if you're looking for a fresh and unusual take on the series, there's Star Trek Manga: the Ultimate Edition, which runs a wide range of styles and themes. They combine the series formula with that manga mainstay, the giant robot, as the Enterprise must take on a whole slew of them in "Orphans." There's a clever (and creepy) tip of the hat to the show's continuity, when the crew encounters a technological virus which they find nearly futile to resist in "Side Effects." They hit the action/adventure vein hard when Kirk and a Klingon captain are trapped together in a collapsed mine in "Art of War" (written by Wil Wheaton, who played Wesley Crusher in the Next Generation series). Of course, it wouldn't be Star Trek without some social commentary, which you get when the men and women of the crew are divided and set against each other in "'Til Death." And, they've even got a story by one of the show's original writers, David Gerrold, recalling some of the humor from his episode "the Trouble with Tribbles."
Finally, I feel obliged to tell you that there is even a Next Generation Manga, if that's your thing.